Natural sound frequencies specify the frequency attributes of sound waves that will efficiently induce vibration in a body or that naturally result from the vibration of that body.

Every object has a unique natural frequency of vibration. Vibration can be induced by the direct forcible disturbance of an object or by the forcible disturbance the medium in contact with an object (e.g. the surrounding air). Once excited, all such vibrators (i.e., vibratory bodies) become generators of sound waves. For example, when struck, the prongs of a simple tuning fork undergo sinusoidal oscillations and generate a sound wave.

Vibratory bodies can also absorb sound waves. Vibrating bodies can, however, efficiently vibrate only at certain frequencies called the natural frequencies of oscillation. In the case of a tuning fork, if a traveling sinusoidal sound wave has the same frequency as the sound wave naturally...